Electric switch



Feb. 11, 1930.

ELECTRIC swITcH Filed July 28, 1927 IA/VEA/To-R' MA n/rms-n 50.4. 15/ 0.4.9 1?

ATTORME-Y.

M. SCHLEI CHER 1,746,363

Patented Feb. 11, 1930 UNITED STATES PATENT OFFICE MANFRED SCHILEICHER, OF BERLIN-CHARLOTTENBURG, GERMANY, ASSIGNOR TO SIE- MENS & HALSKE, .AKTIENGESELLSCHAFT, OF SIEMENSSTADT, NEAR BERLIN, GER- MANY, A. CORPORATION OF GERMANY ELECTRIC SWITCH Application filed July 28, 1927, Serial No. 209,190, and in Germany September 17, 1926.

My invention refers to electrical switching devices and has for its purpose to provide means whereby such devices can be supervised in a particularly effective manner so that their operation can becontrolled and all danger arising from overheating or the like can be avoided.

In modern systems of electric energy distribution substations are frequently consult contact resistances accompanied by a development of heat, whereby the switch can be destroyed altogether. All such defects frequently escape the attention of the i11- specting attendant, more. especially if no high currents arise at the time of inspection.

In order now to obviate these drawbacks and to allow a reliable supervision of the switches without any particular loss of time, I arran e near or on the switch and in heat conductive connection therewith a material which, when a predetermined temperature is exceeded, will undergo a change of color. Materials of this kind are well known and can easily be produced by adding dry dye-stuffs to materialshaving a well defined melting point. When the material is fused, the dyestuif will be dissolved in the molten material and will color it. Thus for instance vanilline, to which some eosin has been added, will assume a rose. color at 82 C., phenanthrone, to which some quinoline yellow has been added, will be colored yellow at 100, arabinose with eosin will assume a purple color at 160 C.

a maximum of contact therebetween.

A mixture of such material and a suitable color or dye-stuff can for instance be placed 1n pulverulent or granular condition in a thin envelope which is then fixed by clamping or otherwise to those parts'of the switch which are particularly exposed to heating. The supervision is facilitated by making the envelope of transparent material. I may, however,'also arrange the material in any cavities of the switch which are then closed by a transparent pane, or the material can be fixed on the switch by painting or by means of an adhesive. If it is desired to control the conditions of operation of the switch in a particularly thorough manner several different materials can be used, which change color at different temperatures.

In the accompanying drawing I illustrate by way of example two ways in which the fusible material may be mounted upon an electric switch, Fig. 1 showing an arrangement wherein the color-changing material is painted or glued onto an element which is adapted to be heated by the current passing through the switch; while Fig. 2 shows a modification of the invention.

In Fig. 1 the numeral 10 indicates the base of an electric switch composed of suitable insulating material upon which is mounted a pair of terminals 11, only one being shown, which are adapted to be connected by a bridge member 12 to close the switch. The bridge member is provided with an extension 13 having a pair of ears 14 thereon adapted to clamp yieldingly therebetween a removable element 15, the extension 13 being bent as shown and the element 15 being of triangular or polygonal cross-section in order to provide The element 15 may be provided with tabs 16 to facilitate mounting and removal of the same.

Upon a face of the element 15 I paint, glue or otherwise apply a layer or coating of a material which undergoes a change of color when heated to a predetermined temperature.

I 20, which may be composed of separate sections 21, 22, 23 containing materials which change color, or fuseand change color, at different temperatures. The cartridge r envelope is preferably made of transparent material so that the changes in color may be observed through sight holes 24. If desired, the cavity in the switch may be so formed as to receive the color-changing material or materials directly, such cavities being closed by means of a transparent material such as that of which the cartridge or envelope 20 is composed.

Various changes may be made in the details disclosed in the foregoing specification without departing from the invention or sacrificing the advantages thereof.

I claim 1. An electric switch havin a cavity and in said cavity a material whic undergoes a change of color on being heated to a predetermined temperature.

2. An electric switch having a cavity and, in said cavity, a material which undergoes a change of color on being heated to a predetermined temperature, and a transparent seal covering said cavity.

3. An electric switch comprising spaced members constitutin a terminal of an electriccircuit, a movable member adjustable into the space between said spaced members into surface contact therewith, and out of said space to make and break the electric circuit, and a plurality of materials carried by said movable member in heat conducting relation thereto, and arranged to undergo changes in color when different predetermined. temperatures are developed by the electric current in said member, whereby defective surface contact between said spaced members and movable member is indicated.

4. An electric switch comprising a part to be heated and a mixture of a material melting at comparatively low temperature and a suitable dye-stufl arranged in heat conductive relation to said part.

5. In combination with an electric switch, an envelope secured to said switch, and a filling enclosed within said envelope and embodying a material which undergoes a change of color when heated to a predetermined temperature.

6. In combination with an electric switch,

a transparent envelope associated with said switch, and a filling enclosed within said envelope and embodying a material which undergoes a change of color when heated to a predetermined temperature.

7 In comblnation with an electric switch, 

